Preparation of cysteine-functionalized graphene quantum dots - Zinc phthalocyanines supramolecular hybrid system and their sono-photochemical studies

Current PDT agents often suffer from low singlet oxygen quantum yields, photobleaching, and poor biocompatibility. To address these issues, we propose novel PDT agents that combine the synthesized phthalocyanines with cysteine-functionalized graphene quantum dots (cys-GQDs) for the first time. This combination aims to enhance singlet oxygen production and improve solubility in biological media. In this way, new zinc phthalocyanines with halogen substituents were synthesized for potential use in photodynamic therapy (PDT). Specifically, 2-Bromo-4-methylphenol zinc (II) phthalocyanine (2a) and 2-chloro-4-methylphenol zinc(II) phthalocyanine (2b) and their graphene quantum dots derivatives were synthesized and characterized. The photochemical, sonochemical, and sono-photochemical properties of these compounds were analyzed, focusing on their efficiency in singlet oxygen production. Our studies of the 2a@cys-GQDs and 2b@cys-GQDs conjugates demonstrated higher singlet oxygen yields, suggesting their enhanced potential for clinical applications.